Why are airlines now declaring there is no room for carry on bags when there is actually plenty of space when boarding the plane?

The airlines started charging for checked luggage. This led many passengers carry on an absurd amount of luggage to avoid paying fees for checking luggage. A prime example would be a family going on vacation where each of the kids has an adult rollerboard that they can’t possibly manage, as well as some type of huge adult backpack which is stuffed with so much clothing they can’t possibly carry it. (Just to be clear, I’m not blaming families traveling like this. I get it. I’m just describing the situation with a common example.)

-Because so many travelers are carrying on to avoid checked luggage fees, there’s much more going into the overhead bins.

-Over time the airlines have reduced the space between economy seats to add extra rows in economy. This results in more passengers sharing the same amount of overhead space. It also makes it more difficult for tall travelers to place items under the seat, which means more second items are going into the overhead bins.

-Airlines are now flying planes with a passenger load closer to capacity than they used to. In the 1970’s, 50% full was common. In this decade, passenger loads are over 80% full as an average.

-Because more seats are in economy, and more people are carrying on more things, it takes longer to load and unload passengers onto the plane. One of the huge snafus that exacerbates the problem is when passengers later in the boarding process get to their seat in the back of the plane and can’t find bin space. They then have to track up to the front of the plane and gate check their bag.

The reason the airlines are constantly making announcements in the gate area is that based on the passenger count, they can tell which flights have a high probability of running out of space for carryon storage. So they offer free gate check because it reduces passenger load times, and reduces the chances of passengers who can’t* gate check their carryon’s getting stuck in a position where the airline has to rebook their flight. Occasionally more passengers than expected take them up on the offer, or the algorithm predicts more hand luggage than passengers are actually carrying, and there’s still extra room at the end of the boarding process.